Packaging material for lithium-ion battery

Abstract

A packaging material for lithium-ion battery comprises a substrate layer made of a plastic film, and a first adhesive layer, a metal foil layer, an anti-corrosion layer, a second adhesive layer and a sealant layer successively laminated on one surface of the substrate layer. The plastic film has a water absorption rate of not less than about 01% to not larger than about 3% when determined by a method described in JIS K 7209:2000 and when the plastic film is subjected to a tensile test (wherein the sample of the plastic film is stored for 24 hours in an environment of 23° C. and 40% R.H., and subjected to a tensile test in the same environment as indicated above under conditions of a sample width of 6 mm, a gauge length of 35 mm and a tensile speed of 300 mm/minute), stress values in an MD direction of the sample and in a TD direction of the sample after stretching by about 10% relative to a length of the sample prior to the tensile test are both from not larger than about 110 MPa and at least one of the stress values in the MD direction of the sample and in the TD direction of the sample is not less than about 70 MPa.

What is claimed is: 
     
       1. A packaging material for a lithium-ion battery comprising:
 a substrate layer made of a plastic film, 
 a first adhesive layer, 
 a metal foil layer, 
 an anti-corrosion layer, 
 a second adhesive layer, and 
 a sealant layer successively laminated on one surface of the substrate layer, 
 wherein the plastic film has a water absorption rate of not less than about 0.1% to not larger than about 3% when subjected to a test described in JIS K 7209:2000, and when subjected to tensile testing, the plastic film having a stress value in a machine direction and a stress value in a transverse direction both not larger than about 110 MPa, and at least one of the stress value in the machine direction of the sample or the stress value in the transverse direction being not less than about 70 MPa, wherein, prior to the tensile testing, a sample of the plastic film is stored for 24 hours in an environment of 23° C. and 40% relative humidity, and subjected to the tensile testing in an environment of 23° C. and 40% relative humidity under conditions of a sample width of 6 mm, a gauge length of 35 mm and a tensile speed of 300 mm/second to measure a stress value at a time when the sample is stretched by about 10% (a displacement of 3.5 mm) relative to a length of the sample prior to the tensile testing, 
 wherein the plastic film contains not less than about 2 mass % to about 30 mass % of a thermoplastic polyester elastomer, and 
 wherein the thermoplastic polyester elastomer comprises a first segment and a second segment, a mass ratio of the first segment to the second segment being 1.0-4.0. 
 
     
     
       2. The packaging material for the lithium-ion battery of  claim 1 , wherein when the sample is stretched, according to the tensile testing of the plastic film, by about 10% relative to the length of the sample prior to the tensile testing, stress values in the machine direction of the sample and in the transverse direction of the sample are both from not less than about 70 MPa to not larger than about 110 MPa. 
     
     
       3. The packaging material for the lithium-ion battery of  claim 1 , wherein the plastic film is made of a polyethylene terephthalate film having a thickness of about 10-40 μm. 
     
     
       4. The packaging material for the lithium-ion battery of  claim 1 , wherein the plastic film is a multi-layer plastic film. 
     
     
       5. The packaging material for the lithium-ion battery of  claim 1 , wherein the first adhesive layer is formed by a curing agent comprising an isocyanate compound. 
     
     
       6. The packaging material for the lithium-ion battery of  claim 1 , wherein the second adhesive layer comprises polypropylene resin which is graft-modified with maleic anhydride. 
     
     
       7. The packaging material for the lithium-ion battery of  claim 1 , wherein the sealant layer comprises polyolefin resin which is graft-modified with maleic anhydride. 
     
     
       8. The packaging material of  claim 1 , wherein the plastic film is a single layer film. 
     
     
       9. A lithium-ion battery comprising a packaging material wherein:
 the packaging material comprises
 a substrate layer made of a plastic film, 
 a first adhesive layer, 
 a metal foil layer, 
 an anti-corrosion layer, 
 a second adhesive layer, and 
 a sealant layer successively laminated on one surface of the substrate layer, 
 
 wherein the plastic film has a water absorption rate of not less than about 0.1% to not larger than about 3% when subjected to a test described in JIS K 7209:2000, and when subjected to tensile testing, the plastic film having a stress value in a machine direction and a stress value in a transverse direction both not larger than about 110 MPa, and at least one of the stress value in the machine direction of the sample or the stress value in the transverse direction being not less than about 70 MPa, wherein, prior to the tensile testing, a sample of the plastic film is stored for 24 hours in an environment of 23° C. and 40% relative humidity, and subjected to the tensile testing in an environment of 23° C. and 40% relative humidity under conditions of a sample width of 6 mm, a gauge length of 35 mm and a tensile speed of 300 mm/second to measure a stress value at a time when the sample is stretched by about 10% (a displacement of 3.5 mm) relative to a length of the sample prior to the tensile testing, 
 wherein the plastic film contains not less than about 2 mass % to about 30 mass % of a thermoplastic polyester elastomer, 
 wherein at least a first sheet of the packaging material is provided with a recess; a cathode, a separator and an anode are placed in the recess; and a second sheet of the packaging material is overlaid over the recess, and 
 wherein the thermoplastic polyester elastomer comprises a first segment and a second segment, a mass ratio of the first segment to the second segment being 1.0-4.0. 
 
     
     
       10. The lithium-ion battery of  claim 9 , wherein the plastic film is a single layer film.